Light exposure and sleep

It’s commonly known that a dark bedroom is better for good sleep, but perhaps less well-known is the impact of light exposure on our sleep quality in the run-up to bedtime.

Light is one of the main environmental influences on our body’s circadian rhythm, and is particularly powerful in kick-starting the production of energy-providing hormones required to stay awake and active throughout the day. In short, light signifies to the body that it’s daytime, and the body responds to this by waking up. Conversely, fading light and eventual darkness indicates night-time and a need for sleep. This process is effective when the light is natural sunlight, as this is more or less regular, with slight variations dependent on the seasons. Where it becomes problematic is through sustained exposure to artificial light at all hours, from TVs, computers and increasingly illuminated smartphones and tablets. Due to their wide-ranging functionality – they’re used for work and play - the times that we use these devices are rarely restricted. So it’s not uncommon for many people to spend some time on their phone just prior to going to bed. In fact, the portability of phones and tablets mean that they can be comfortably used in bed, and for lots of people the last thing they see before closing their eyes is the super-illuminated screen of their mobile.

These technological marvels emit what’s know as blue light, which is effectively the same intensity as natural sunlight as far as our eyes are concerned. This means that spending an hour or so looking at a website on your phone or tablet in the late evening is effectively sending powerful signals to your brain that it’s not time to go to sleep, it’s actually day-time and the body needs energy. This leads to an uncomfortable period when you do go to bed, where you lie awake with racing thoughts and sleep being the furthest thing from your mind.

The solution to this problem is of course simple – limit your body’s exposure to artificial light in the evening. By spending an hour or two before bedtime in a low light environment you’re priming your body for sleep. If you absolutely can’t resist looking at your smartphone in the evening, it’s important to reduce the brightness levels to less than 20%, and limit the time spent on it to as short as possible. That way you’ll prevent sending powerful light signals to your body and give yourself a good chance of relaxing into deep sleep quickly and easily.